On Fri, Jan 23, 2015 at 12:58:27PM +0100, Vincent Bernat wrote:
> Same, but:
>
> $ cat /proc/1/smaps
> cat: /proc/1/smaps: Permission denied
A user, any user, is able to open that file. However only some users can
read the file.
This is strace of more /proc/1/smaps the open succeeds but the read
fails.
open("/proc/1/smaps", O_RDONLY) = 3
fstat(3, {st_mode=S_IFREG|0444, st_size=0, ...}) = 0
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) =
0x7f8c6c9cc000
lseek(3, 0, SEEK_SET) = 0
read(3, 0x7f8c6c9cc000, 1024) = -1 EACCES (Permission denied)
The tests are correctly detecting something. Something in the kernel has
changed (yet again) meaning that pmap's behaviour has changed, failing
the test.
If you run the exact same command on my computer and your computer,
you will get a different result.
Interestingly, cat gives permission denied, more does not though it
doesn't print anything either.
Can you strace pmap -X 1 and send me the output?
What I'm looking for is, in my strace
line 86
open("/proc/1/smaps", O_RDONLY) = 3
then 94,96
fstat(3, {st_mode=S_IFREG|0444, st_size=0, ...}) = 0
read(3, 0x7f7026b42000, 1024) = -1 EACCES (Permission denied)
This is equivalent of the fopen() working in one_proc and the read()
failing in print_extended_maps
I suspect that something strange is going on with the open()
--
Craig Small (@smallsees) http://enc.com.au/ csmall at : enc.com.au
Debian GNU/Linux http://www.debian.org/ csmall at : debian.org
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